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AR# 14860

System ACE CF - How do you exclusively select the configuration data source to be CF, MPU or JTAG? (need clarification of Table 27 in data sheet v1.5)

Description

General Description:

In the System ACE CF Data Sheet (DS080 v1.5), Table 26 and Table 27 (page 35) show the device pins (CFGMODE and CFGADDR<2..0>) and the internal register bits which control the configuration mode. Table 27, in particular, shows how to set these control signals up for a particular active configuration mode. The entries for Table 27 are as follows:

CFGRESET - Configuration/CompactFlash controller reset, and a subset of the RESET pin (default is 0):

0 - means do not reset

1 - means reset the Configuration and CompactFlash controllers (this also causes a soft-reset of the CompactFlash device)

NOTE 1: The CFGMODE pin is only taken into account when the FORCECFGMODE bit = 0 (default).

If the CFGMODE pin = 0, you can override that by setting the FORCECFGMODE = 1 and CFGMODE = 1.

NOTE 2: The control is switched to the TSTJTAG port after any configuration process is complete, regardless of the configuration mode selected.

The following examples should help to clarify:

For the following settings:

CFGMODE = 1

CFGSEL = 0

CFGSTART = 0

CFGRESET = 0

This seems to either invoke the CF or TSTJTAG configuration. If the FORCECFGMODE bit = 1 and CFGMODE = 1 (or the CFGMODEPIN pin = 1), and the CFGSEL = 0. then the CF configuration mode will be selected. After the chip is configured in the CF mode the control is switched to the TSTJTAG port. See the heading "CompactFlash (CF) to Configuration JTAG (CFGJTAG) Setup" in the data sheet for this flow.

For the following settings:

CFGMODE = 1

CFGSEL = 1

CFGSTART = 0

CFGRESET = 0

This could be interpreted as MPU mode or the TSTJTAG mode. The answer is as above. If the FORCECFGMODE bit = 1 and CFGMODE = 1 (or the CFGMODEPIN pin = 1), and the CFGSEL = 1, then the controller will be set to the MPU configuration mode. After the chip is configured the TSTJTAG port is active. You can find the flow in the data sheet under the heading "Microprocessor (MPU) to Configuration JTAG (CFGJTAG) Setup."

For setting the TSTJTAG configuration mode use:

CFGMODE = 1

CFGSEL = 0

CFGSTART = 0

CFGRESET = 0

Again, the CFGMODE pin is only taken into account if the FORCECFGMODE bit = 1. The TSTJTAG port is available under these settings until the CFGRESET bit or RESET pin is toggled (then the controller will switch to the CF as the configuration source). For the TSTJTAG flow, see the section under the heading "Test JTAG (TSTJTAG) to Configuration JTAG (CFGJTAG) Setup" in the data sheet.